The March 20–22, 2018 nor'easter, dubbed the "Four'easter" in some media outlets) brought additional significant late-season snowfall to the Northeastern United States, after three previous such nor'easters had struck the general region on March 1–3, 6–8, and 12–14, respectively. affected the Mid-Atlantic states and New England with over of heavy snow and whiteout conditions. It also affected areas of the Southeastern and Midwestern United States with both snowfall and severe weather. The nor'easter was also one of the heaviest spring snowstorms on record in some areas in the Mid-Atlantic, especially Philadelphia and New York City.
Originating from a surface low that formed over the Rocky Mountains, the system tracked across the central United States, bringing some wintry weather to surrounding areas as well as severe weather in the South. It then reached the Northeastern U.S. on March 20–21 and, while moving slowly near the shorelines of Delaware, New Jersey, and Long Island, dropped heavy snowfall with rates of up to an hour in some spots. The storm was given unofficial names such as Winter Storm Toby and Nor'easter 4.
The storm caused hundreds of flights to be cancelled in advance, and caused many school districts to close for the following day or two. Over 100,000 power outages were reported as a result of the nor'easter. At least 3 people have been killed in the nor'easter as of March 21. In addition, the system produced a tornado outbreak in the Southeast, spawning at least 20 tornadoes on March 19, one of which was a long-tracked EF3 that hit Jacksonville, Alabama causing considerable damage.
Meteorological history
On March 18, an area of low pressure consolidated over the Rocky Mountains, bringing moderate to heavy snow to those locations. Over the next day or two, this low slowly moved eastward across the Central United States, while also interacting with a stationary front located in the Southeast. This ultimately resulted in a severe weather outbreak in the South late on March 19, producing at least nineteen confirmed tornadoes, one of which was rated an EF3. As the system moved eastwards towards the Eastern United States, it was still somewhat uncertain how much snow the storm would produce, which depended on its track and intensity; as the impending storm grew closer it became increasingly likely a major snowstorm would occur. Precipitation began to spread into the Mid-Atlantic states by early March 20. This first phase of the nor'easter brought freezing rain and snow to much of the Tri-State area, before it began dissipating later that night while snow continued over the Appalachian Mountains from an associated but weakening low. At the same time, a new surface low formed off the Chesapeake Bay around 03:00 UTC on March 21, prompting the Weather Prediction Center (WPC) to begin issuing storm summaries on the developing nor'easter.
After forming, the storm began intensifying as it slowly moved northward parallel to the East Coast, with a large swath of moderate to heavy snow covering the area of New Jersey and Long Island in the morning hours of March 21. Contrary to the previous nor'easters, there was colder air further south then in other storms, which allowed accumulating snow to stick more quickly in areas near southern New Jersey throughout the day. Due to moving slowly near the coast, bands of heavy snowfall (with some embedded rates of up to per hour) hammered the coastline as it continued to slowly move eastward. By the following day, the system attained a minimum pressure of around . Shortly afterwards however, at 15:00 UTC, the WPC terminated storm summaries on the nor'easter as most of the snow in New England had tapered off.
Preparations and impact
Mid-Atlantic regions
Having been affected by three previous nor'easters in the month of March, the impending storm caused intense preparation across the region. In the early morning hours of March 20, several hundred flights were either canceled or rerouted ahead of the storm. More than 4,000 flights were canceled on March 21, mainly because of the nor'easter. Amtrak modified or canceled service on several trains running along the Northeast Corridor on March 21 and 22 due to the nor'easter. Over 100,000 people lost power from the nor'easter.
Virginia and Maryland
In Virginia, state offices in Richmond opened two hours late on March 21. The Virginia State Police responded to more than 250 crashes on the morning of March 21. Virginia Railway Express suspended service on March 21 due to the snow.